基于钙超载研究滇乌碱诱导大鼠心律失常的毒性机制

Study on the Toxicity Mechanism of Yunaconitine-induced Arrhythmia in Rats Based on Calcium Overload

目的:研究滇乌碱诱导大鼠心律失常的毒性机制。方法:将32只大鼠按随机数字表法随机分为正常对照组,滇乌碱低、高剂量组(0.09、0.14 mg/kg)和乌头碱组(阳性对照,0.88 mg/kg),每组8只。各给药组大鼠每天灌胃相应药物1次,正常对照组大鼠灌胃等体积生理盐水,连续7 d。末次灌胃后,观察各组大鼠的心电图变化,测定大鼠心肌组织中腺苷三磷酸(ATP)含量、心肌细胞中Ca^(2+)含量、心肌组织中Na^(+)-K^(+)-ATP酶和Ca^(2+)-Mg^(2+)-ATP酶活性以及雷诺定受体2(RyR2)、Ca^(2+)-ATP酶(SERCA2)蛋白表达水平。结果:与正常对照组比较,滇乌碱低剂量组大鼠QRS波时限、校正后QT期间(QTc间期)均显著延长(P<0.01),心肌细胞中Ca^(2+)含量显著升高(P<0.05),心肌组织中ATP含量、Ca^(2+)-Mg^(2+)-ATP酶活性、Na^(+)-K^(+)-ATP酶活性和SERCA2蛋白表达水平均显著降低(P<0.05或P<0.01);滇乌碱高剂量组和乌头碱组大鼠心率均显著增快(P<0.05或P<0.01),QRS波时限、QTc间期均显著延长(P<0.01),心肌细胞中Ca^(2+)含量均显著升高(P<0.01),心肌组织中ATP含量、Ca^(2+)-Mg^(2+)-ATP酶活性、Na^(+)-K^(+)-ATP酶活性和RyR2、SERCA2蛋白表达水平均显著降低(P<0.01)。结论:滇乌碱可导致大鼠心律失常;其作用机制可能与降低心肌组织中Ca^(2+)-Mg^(2+)-ATP酶、Na^(+)-K^(+)-ATP酶活性,下调心肌组织中钙转运相关蛋白RyR2、SERCA2的表达,从而导致Ca^(2+)超载有关。

OBJECTIVE:To study the toxicity mechanism of yunacotine-induced arrhythmia in rats.METHODS:Totally 32 rats were randomly divided by random number table method into normal control group,yunacotine low-dose and high-dose groups(0.09,0.14 mg/kg),aconitine group(positive control,0.88 mg/kg),with 8 rats in each group.Administration groups were given the corresponding drugs once a day,and normal control group was given the constant volume of normal saline,for consecutive 7 d.After last intragastric administration,the changes of electrocardiogram(ECG)were observed.The contents of adenosine triphosphate(ATP)in myocardial tissue and Ca^(2+)in myocardial cells,the activities of Na^(+)-K^(+)-ATPase and Ca^(2+)-Mg^(2+)-ATPase as well as the protein expression of ranolidine receptor 2(RyR2)and Ca^(2+)-ATPase(SERCA2)in myocardial tissue were determined.RESULTS:Compared with normal control group,time limit of QRS wave and QTc intervals of rats were prolonged significantly in yunaconitine low-dose group(P<0.01).The content of Ca^(2+)in myocardial cells,the ATP contents,the activities of Ca^(2+)-Mg^(2+)-ATPase and Na^(+)-K^(+)-ATPase as well as the protein expression of SERCA2 in myocardial tissue were reduced significantly(P<0.05 or P<0.01).The heart rate of rats in yunaconitine high-dose group and aconitine group were increased significantly(P<0.05 or P<0.01),and time limit of QRS wave and QTc intervals were significantly prolonged(P<0.01);the content of Ca^(2+)in myocardial cells was increased significantly(P<0.01);ATP content,the activities of Ca^(2+)-Mg^(2+)-ATPase and Na^(+)-K^(+)-ATPase,and protein expression of RyR2 and SERCA2 in myocardial tissue were decreased significantly(P<0.01).CONCLUSIONS:Yunaconitine can induce arrhythmia in rats,the mechanism of which may be associated with Ca^(2+)overload that resulted from reducing the activities of Na^(+)-K^(+)-ATPase and Ca^(2+)-Mg^(2+)-ATPase and down-regulating the expression of related calcium transporter RyR2 and SERCA2.